California Rice Production Workshop, v15

Variety Selection and Management Introduction and History

Since its beginning in 1912, California’s rice industry limited its production and marketing largely to a few short and medium grain japonica varieties, developed from stocks originating in Japan and China. These varieties produced good yields of quality rice in the dry, temperate climate of the Sacramento and San Joaquin Valleys. For the grower, the choice of variety to plant was relatively simple because the few varieties available were similar in performance, yield potential and milling quality when properly managed. Included were Colusa, Caloro and Calrose released in 1918, 1921 and 1948, respectively, and Earlirose, a productive, early maturing, proprietary variety, released in 1965 which soon became a popular variety for cold areas and/or late plantings. These were the major rice varieties grown in California until the early 1970’s.

Then, the variety picture began to change significantly. A powerful impetus for this was the enactment of California Rice Research Marketing Order that established the California Rice Research Board in 1969. This grower initiative provided significant and regular funding to hasten development and release of new varieties. The medium grain variety CS-M3 was released in 1970 and the short grain variety CS-S4 in 1971, from rice hybridizations made in 1946 and 1957 at the Rice Experiment Station (RES) at Biggs, CA. CS-M3 gained wide acceptance and competed with the older Calrose for acreage. But, CS-S4, though an improvement over Caloro, was not widely grown because of its susceptibility to low temperature induced sterility. The last tall stature variety from the RES breeding program, M5, was released in 1975.

In 1976, Calrose 76, the first short stature (semidwarf) California rice, was released. This late maturing medium grain variety was a radiation induced mutant selected by the USDA in Davis in 1971. It was soon followed by the semidwarf M9, developed by hybridizing the tropical “green revolution” variety IR-8 by the RES. Thus began the era of short stature rice in California, which was to have enormous consequences. Subsequently, numerous varieties have been released in a range of maturity groups with different grain shapes and culinary characteristics. More detailed historical information regarding California varieties is given in Appendix A.

Acreage

Publicly developed and introduced rice varieties are grown annually on about 96% of the planted acres, and over twenty proprietary varieties are grown on the rest. See Appendix B for 1988 - 2004 acreage of varieties. Most varieties growing in California are short and medium grain japonica types with origins from the cooler rice climates of the temper3.1

Publicly developed and introduced rice varieties are grown annually on about 96% of the planted acres

California Rice Production Workshop, v15

ate latitudes. About 80% of the acreage is planted to ‘Calrose’ type medium grain varieties destined for a host of purposes including table rice and manufactured uses. California short and long grain varieties are also planted on one to two percent of the acres. Premium quality medium and short grain rice is grown on 10-11% of acres, and is destined for higher price table rice markets. Additional small acreages of specialty varieties are also planted, such as sweet rice (also called mochi, glutinous or waxy), arborio types, and aromatic long grains including conventional and a basmati type.

Naming System for Public Varieties in California

In 1979, the California rice industry developed a uniform naming system for new, public ally developed rice varieties, based on grain type, maturity group and order of release. This was necessary to avoid confusing the large number of varieties to prevent mixing of different type grains and to avoid inappropriate planting dates. Varieties should be referred to by their complete letter, numerical and descriptive name because deleting any component may lead to serious errors.

The name of a new variety contains a prefix letter designating its grain type as long (L), medium (M) or short (S). Specialty rice will carry a descriptive word prefix, such as Calmochi for waxy or sweet rice, Calmati for basmati-like rice, Calhikari for premium quality short grain rice, Calamylow for low amylose (≈7%) type rice, and A for aromatic rice. Immediately following the letter or name descriptor is a three digit number separated by a dash (-) from the letter or name. The first digit in the number designates the maturity group as either 1 (very early), 2 (early), 3 (intermediate) or 4 (late). The last two digits indicate the order of release of this type, from 01 to 99, starting in 1979 when this system began. For example, M-202 indicates an early maturing medium grain variety which was second in order of release.

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Table 1. Outline of the California foundation and grower owned rice variety naming system and varieties grown in 2014. Grain type letter(s) are combined with a numeric descriptor. The first digit is the maturity group, the others are the order of release. Grain Type Short (S)

Medium (M)

Long (L)

Very Early Early (100-199) (200-299) S-102 M-104 M-105

-

Intermed. (300-399) -

Late (400-499) -

L-206

-

-

A-201 A-202

A-301

-

-

-

CT-201 CT-202

-

-

M-202 M-205 M-206 M-208 M-209

Calmochi sweet rice (CM)

CM-101

CM-203

Calhikari short premium (CH)

-

Calmati basmati type (CT)

-

CH-201 CH-202

Aromatic (A)

-

Calamylow (CA)

-

-

M-401 M-402

-

CA-201

Proprietary and Introduced Varieties

In addition to the publicly developed varieties, some varieties of Japanese origin are also grown and retain their Japanese name, such as Akitakomachi and Koshihikari. Several companies also introduce or develop varieties for California while others have introduced varieties with unique characteristics such as colored bran, aroma, and special culinary properties. There are approximately 21 such proprietary varieties. They are named by the proprietor.

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Ownership

Table 2. Proprietary and introduced rice varieties in California. Short

Proprietary

Calpearl NFD 108 NFD 109 SP-2 Surpass WRS-4431 A-17 A-20 S-6 Vialone Nano Carnaroli

Introductions

Akitakomachi Hitomibore Koshihikari Sasanishiki Koganemochi Himenomochi

NFD-181 85-101-10 91-130-02 94-158-01 95-164-01 KR-4 Kukuhorose Millrose SP-211 SP-311 SP-411 WRM-3538 Arborio Calriso Baldo Guadiamar Riz Rouge Camargue

Medium

02-PY-021 02-PY-014 RRI-321 RRI-226 98-102 02-121& 120 04-116 & 302 LMR-206 FRC-11 & 22 00-117 07-122 LBJ-115

Rojito (SunWest)

Long

Donana P-2 Denosa P-3 Isla

Wehani Lundberg Black Japonica HongKong Black Black Rice Aromatic Red

Grain and Plant Characteristics Important for Management

Successful production and marketing of rice requires knowledge of plant and grain characteristics. Since a rice grower’s first concern is usually the market for which the crop is intended, primary consideration must be given to grain shape, appearance and culinary characteristics. Second, yield performance is usually an important criterion for variety selection, although for certain varieties, market quality outweighs yield. Varieties should also be chose on the basis of their relative maturity so they can fit the cropping schedule of a particular farming operation or are suitable to a particular climatic condition. For example, late maturing varieties fit early planting schedules; cold tolerant varieties are needed for cooler areas. Agronomic characteristics, such as lodging and nitrogen response may also be considered in addition to straw quantity and quality and pubescence (rough or smooth leaf and hull). Currently, no California varieties have insect or herbicide resistance, but will in the future, which may become a primary selection criterion. Rice plant and grain characteristics are discussed below.

Grain Characteristics Grain Shape

Rice grains are classified as short, medium or long grain. The specific size and shape classification limits of brown rice kernels are shown in Table 3.

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Table 3. Approximate size and shape classifications for California rice varieties, brown basis.* Rice Class

Premium short Short

Premium medium Medium Arborio Long

Aromatic

Basmati type Mochi

Length (mm)

Width (mm)

Length/width

Kernel wt. (g/1000 kernels)

5.5

3.3

1.7

27.6

5.2 6.7 6.1 6.3 7.8 8.2 7.5 5.3

2.8

1.8

3.0

2.2

2.9

1.9

3.3

1.9

2.2

3.5

2.1

3.9

2.1

3.6

3.0

1.8

20.2 23.9 23.8 25.3 21.5 23.1 21.0 23.9

*Adapted for California varieties from the publication “Production of Quality Rice in South Eastern Australia” (Chapter 13)

Grain Quality

Milling, market and cooking/culinary qualities are mentioned here because they are influenced by varietal selection and management methods. For example, genetic characteristics influence milling quality, which will influence choice of variety. In addition, many quality components of Japanese premium short grain varieties are influenced by production practices. Grain Starch Content

Amylose is a straight chain glucose molecule, as contrasted to amylopectin, a larger highly branched glucose molecule. In general, the more amylose a variety has, the less sticky. The majority of California rice is Calrose type medium grain and has low amylose content which tends to make it soft when cooked and the grains tend to stick together. “Calrose” is a marketing term that refers to all non-premium quality medium grain rice varieties with cooking/culinary characteristics similar to the original Calrose variety. Demand for Calrose varieties remains strong, and they occupy over 80% of the state’s acreage. California nonpremium short grain rice also has low amylose and cooks similarly to Calrose and is used as table rice, brown rice, and rice cakes.

Long grain rice in California has higher amylose than medium and short grain which imparts a firm, dry characteristic when cooked. Most California long grain varieties released to date tend to cook softer than their Southern counterparts and are not generally sold in typical long grain markets, although the goal is to develop a long grain variety adapted to California with Southern US cooking characteristics.

Scent: Aromatic and Basmati Types

A few California varieties, such as A-301, are known as aromatic and have a distinctive scent, similar to popcorn, particularly when cooked. 3.5

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The scent is also discernible in the field. It is from a high 2-acetyl-1pyrroline content compared to non-aromatic varieties. In addition to aroma, Basmati-type varieties (Calmati-201) also have a cell wall arrangement in the grain that results in grain lengthening during cooking as compared to other varieties which tend to expand uniformly when cooked. Otherwise, they have amylose starch content similar to other long grain varieties. Aromatic and Basmati type rice sells in a unique market. The presence of aroma makes it very important to maintain identity preservation of aromatic varieties to avoid mixtures with non-aromatic types. Arborio/Chalky Types

Arborio is the name of a short grain variety from Italy and a market type for similar varieties grown in California. This type is characterized by having a very large kernel, and an excessive amount of chalkiness which is the presence of white, opaque areas within the milled kernel, as contrasted to the translucent whiteness of most varieties. Chalk is a heritable defect and is one of the first things rice breeders eliminate in most varieties because it results in low milling yields and poor appearance. Chalk is referred to as white belly and other names, depending on the position of the chalk on or in the milled kernel. But for Arborio, chalk is associated with superior culinary properties for specific dishes, primarily risottos. Other than genetics, chalkiness is caused by high harvest moisture, uneven ripening, and cultural practices that result in uneven ripening and presence of immature kernels at harvest.

Specialty varieties currently grown include aromatic rice (conventional, basmati type), arborio type (large, chalky grain), mochi, which has no amylose, and colored bran (red or nearly black). The latter has little or no amylase.

Plant Characteristics Relative Maturity.

Maturity of California rice varieties is classified by the number of days from planting to 50% heading in the warmer areas of the state. Four categories are used, Table 5. Maturity differs primarily in the length of the vegetative stage. Beyond the 50% heading Table 4. Relative maturity groupings of rice varieties point, California short and medium grain varigrown in warm areas. eties normally require another 40 to 55 days for grain maturity in warm areas, and 5 to 15 Maturity Group Days to 50% heading days more in cool areas. Long grain varieties Very Early < 90 usually ripen 5 to 10 faster after 50% heading than medium grain varieties. Maturity is relaEarly 90 to 97 tive and can be advanced or delayed by plantIntermediate 98 to 105 ing date, nutritional status, temperature and other environmental factors. Late > 105 3.6

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Very early varieties are commonly grown in cooler areas and for late planting when later varieties are not well-suited. An increasing practice is to plant them early in warm areas to advance harvest to allow more time for straw management and to shorten the water season. Maintenance of milling quality can be more of an issue when very early varieties are planted early.

Early varieties occupy roughly 70-75% of the acreage. They are predominately Calrose type and are generally higher yielding varieties. Early varieties provide flexibility because they are suited to a wide range of planting dates.

Intermediate maturity varieties were intended to provide a more timely harvest sequence. However, there are few representatives in this category because of the industry preference for earliness.

Late maturity varieties were also intended to provide options for harvest sequencing. However, most late varieties currently grown are used because they have particular characteristics, such as premium quality, rather than for their value in scheduling harvest. They are generally planted before May 1. About 10% of the acres is typically planted to late maturing varieties. Seedling Vigor

Seedling vigor refers to early growth and includes rapid leaf emergence through the water, stand density, growth rate after emergence, leaf droopiness, and leafiness. Vigor is an important component in variety evaluation because it helps improve stand establishment. For the grower, vigorous varieties make water management easier and may improve competition against weeds. California varieties vary in their vigor over a fairly narrow range, with the long grains having less vigor than medium and short grains. Plant Height

Plant height is the distance between the soil surface and the tip of the erect panicle. Height is important because of its relationship to plant physiological processes and lodging which affects harvestability and yield. Height classifications include short, intermediate and tall. Short stature varieties at average soil fertility are less than 95 cm; intermediate stature varieties are 95-105 cm; and tall varieties are taller than 105 cm. Prior to 1976, all California varieties were tall and tended to lodge, particularly under high nitrogen fertility. Beginning with the release of Calrose 76, all varieties from the public program have been short stature. Since full adoption of short stature varieties from 1976 to about 1980, statewide average yields rose dramatically.

Pubescence of Hulls and Leaves

The predominant hull trait important to producers is the presence or absence of hairs. Pubescent/hairy/rough varieties have numerous hairs 3.7

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called trichomes distributed over the flower, seed covers and leaf surfaces. Glabrous/smooth varieties have a few hairs on the keel of the hull and the margin of the leaves, but are otherwise smooth. Before heading, smooth and rough varieties can be distinguished by running a leaf blade between thumb and finger and noting whether its surface (not edge) is rough. Of importance to producers is the fact that smooth varieties have a higher bulk density (test weight) than hairy varieties and result in heavier trucks which can be easily overloaded; and tighter packing in bin driers requires more pressure to move air compared to rough varieties. Smooth varieties are also less dusty during harvest and drying, resulting in less discomfort for harvest and drier personnel. With the exception of CM-101, CH-201, CT-201, and S-102, all public California varieties are smooth. Both Koshihikari and Akitakomachi are rough hulled. Awns

Varieties may have long, medium, or short awns, or be awnless. The characteristic is under genetic, and to some extent, environmental control. The importance of awns for producers is in harvesting. Awns on some varieties may be difficult to remove resulting in lower bulk density and difficulty in unloading harvesters due to bridging, especially pubescent varieties. Photoperiod Response

Some rice varieties respond to the length of the day, the time between sunrise and sunset. This is the photoperiod. The transition from vegetative to reproductive growth is triggered by day length in photoperiod sensitive varieties which are mostly grown in the tropics. However, with the exception of M-401, most rice grown in temperate zones, including California, is generally insensitive to photoperiod, and responds primarily to temperature. Tolerance to Low Temperature Sterility

Low temperatures during formation of the pollen mother cell (microsporogenesis) is a primary cause of panicle sterility (blanking). This physiological stage coincides with the time when the collar of the flag leaf is adjacent to the penultimate leaf (next to the last leaf), and when the panicle is still entirely inside the boot. The cause is low temperature for a sufficient duration, particularly if it occurs for several successive nights. While many combinations of time and temperature can cause blanking, an overnight low of 55° or lower can be used as an alert that temperatures may be low enough to cause damage. All varieties are screened for tolerance to blanking. Table 5 gives approximate ranking of varieties by their general level of sterility tolerance.

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Table 5. Relative ranking of Public California rice varieties for cold temperature sterility tolerance Low

Calmati 201 Calmati 202

Fair

M-205 M-208 L-206 M-401 Calhikari 201 Calhikari-202 A-201 Koshihikari M-402

Good

S-102 M-202 Akitakomachi M-209 Calmochi-203

Excellent M-104 M-206 CM-101

Pest Resistance

Resistance to diseases is a long term goal of rice plant breeding. To date M-208 is the only blast resistant variety in California. Relative levels of stem rot resistance are given in Appendix C, and all fall within a fairly narrow range. Efforts are progressing to improve resistance to stem rot and blast. Suitable lines are being used but the problem continues to be in recovering good agronomic characteristics.

Characteristics of Varieties

A concise description of currently grown public varieties, giving important agronomic characteristics, is in Appendix C.

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Management of Rice Varieties Planting Date

Suggested planting dates for public varieties are given in Table 6. These suggestions assume average weather conditions will prevail. Within the preferred planting date range the variety should perform well if other conditions are optimum. Planting outside these ranges increases risk of weather related damage. Planting dates are not rigid and many growers accept the risk and successfully plant outside these ranges. They are meant as a guideline. Warm areas in Table 6 refer to the Sacramento Valley north of Highway 20 and west of Highway 99. Cool areas include south of Highway 20 and east of Highway 99. Cold areas include south Natomas and Escalon areas.

Variety by Maturity Group Very Early S-102 M-104 CM-101 CM-203 Early M-201 M-202 M-204 M-205 M-206 M-208 M-209 L-204 L-205 L-206 Calhikari-201 Calhikari-202 A-201 A-202 Calmati-201 Calmati-202 Akitakomachi Koshihikari Late M-401 M-402

Table 6. Suggested planting date ranges for public varieties. Preferred Date Range

Optimum

Comments

May 1 - May 25 May 1 - May 25 May 1 - May 20 May 1 - May 20

May 10 May 10 May 5 May 5

May 5 May 5 - 10 May 5 May 5 May 5 - 10 May 5 - 10 May 5 - 10 May 5 May 5 - 10 May 5 - 10 May 5 May 5 May 5 May 5 May 5 May 5 May 5 May 5

Avoid early planting in warm areas with all very early varieties. Advance all dates 5-10 days in cool areas. CM-203, slow grain filling

Avoid cool areas Avoid cold areas For warm areas For warm areas Adapted to most areas Avoid cold areas Avoid cool areas For warm areas Suited to all but cold areas Avoid cool areas Avoid cool areas Avoid cool areas and excess nitrogen For warm areas Avoid cool areas Avoid cool areas Avoid cool areas For most areas Avoid cool areas

April 20 - May 10 April 20 - May 5

May 1 May 1

For warm areas For warm areas

April 25 - May 20 April 20 - May 25 April 25 - May 20 April 25 - May 20 April 20 - May 25 April 20 - May 25 April 20 - May 25 April 25 - May 20 April 20 - May 20 April 20 - May 20 April 25 - May 20 April 25 - May 20 April 25 - May 20 April 25 - May 20 April 25 - May 20 April 25 - May 20 April 20 - May 20 April 20 - May 20

Seeding Rate

Short stature rice varieties perform well at uniform densities of 10 to 20 vigorous plants per square foot. However, many rice fields have plant populations over 30 plants. Plant density can be quite variable and still 3.10

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produce optimum yield. For example, approximately 40 productive tillers per square foot, each giving 100 grains, will produce about 10,000 lbs/ac. The rice plant responds to different populations. Low density planting increases tillering, whereas high density reduces tillering so that the number of panicles per square foot remain fairly constant across a wide range of planting rates. In addition, the number of kernels per panicle also increases or decreases, depending on the density of the panicles. Modern rice fields are usually sown heavily to provide quick cover, weed competition and insurance against catastrophic stand loss. Research has shown that seeding rate, within a wide range, does not dramatically affect yield, assuming normal growing conditions. Table 7 shows the approximate seed population of different varieties when sown at a range of common planting rates. At all sowing rates, the number of seeds is much higher than needed for healthy stands if all the seeds made strong seedlings. However, the consequence of too dense planting is primarily cost although some data suggests that stem rot severity may increase in dense stands. While seed cost remains low in California, growers may continue to use high seed rates without great penalty. Variety

Akitakomachi Koshihikari CH-201

CM-101 CM-203

1000 kernel wt. grams

125

23.8

55

26.2 26.0 29.1

50 51 45

Seeding rate - lbs/ac 150

175

200

66

77

88

60 62 54

70 70 63

80 81 72

S-102

34.0

38

46

54

61

M-202

29.0

45

54

63

72

M-104 M-205 M-206 M-209 M-401 M-402 A-301 A-201

CM-203

30.2 30.7 25.0 29.7 32.0 27.7 28.0 29.0 31.2

43 42 52 44 41 47 47 45 42

52 51 62 53 49 56 56 54 62

60 59 73 61 57 66 65 63 58

69 68 83 70 65 75 74 72 67

Table 7. Approximate number of seeds per square foot of different varieties sown at four different rates in water seeded rice. * *Values estimated from published variety release articles and supporting data.

Nitrogen Rates for Different Varieties

Varieties differ in their nitrogen (N) requirements, particularly when comparing short stature Calrose and short grain types to taller premium short and medium grain types, and certain proprietary tall varieties, 3.11

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such as Kokuhorose. The yield of grain + straw (biological yield) is similar for tall and short varieties. However, with short varieties, more of the biological yield is grain, due to more efficient partitioning of plant energy (photosynthates). In addition, they do not lodge as easily under high N fertility. Both higher efficiency and less lodging result in higher yield than tall varieties. Recent field trials have demonstrated small differences in N requirements among common short stature varieties. In Table 8 preplant N rate is given relative to the rate required for maximum yield of M-202 at several locations. M-202 is a commonly grown rice variety for which most growers have knowledge of the rate to apply. For example, if one were planting M-205, they would use 96% of the rate they would for M-202. Additional experience may change these numbers somewhat. Variety

Number of Locations

N rate as a % of M-202

CT-201

3

89

CH-201 L-205

M-104 M-205 M-206 M-402 S-102

3

75

3

114

6

102

6 2 3 2

104 96 95 93

Table 8. Response to preplant N rates of common California rice varieties, as a percent of M-202.

Rice Certification Law

California’s complex market and variety situation requires procedures to ensure that different types of rice do not get mixed. In addition, transgenic varieties with unique production and quality traits are on the horizon, although none are currently grown commercially in California. While biotechnology has enormous potential to create rices with a wide variety of nutritional, medicinal and industrial uses, it is important to prevent mixtures with other, similar-looking rices that are not transgenic. Processors are demanding assurances of purity in response to the consumer reaction to transgenic crops, particularly in export markets. Hence, the California rice industry sponsored the California Rice Certification Act of 2000 to ensure consistently high quality of California rice, maintain consumer confidence, and enhance and protect California’s reputation as a provider of high quality rice.

The Rice Certification Act of 2000 (Assembly Bulletin 2622) was signed into law on September 22, 2000 and its provisions will go into effect for 3.12

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the 2003 crop year. This legislation contains both mandatory and voluntary identity preservation (IP) components allowing for the certification of any verifiable attribute of rice. The California Rice Commission (CRC) recognized that “There is a growing need to maintain the identity of various types of rice to satisfy increasing consumer demand for specialty rice varieties. This demand requires providing the industry with the ability to establish the terms and conditions for the production and handling of rice in order to minimize the potential for the commingling of various types of rice, and in order to prevent commingling where reconditioning is infeasible or impossible.” All rice varieties for commercial production in California possessing “traits of commercial significance” will be required by statute to be produced within an IP certification system. The cost of the mandatory program will be borne by the growers of the specialty rice seed and grain. The CRC is empowered to collect fees, receive and investigate complaints, provide notice of action regarding alleged violations, and seek injunctive relief and other legal means to prevent violation of the Act. The Rice Certification Act is an example of a product-based IP system.

Any characteristics that may adversely affect the marketability of rice if mixtures occur are defined as having “commercial impact.” Included are those that can be visually identified (e.g., bran color, grain shape, grain size, etc.) or that require specialized equipment to determine their identity or composition (e.g., lab cooking tests, taste panels, DNA or specific protein tests). For example, if rice with red bran were mixed with Calrose type medium grain, the mixture would have lower value, and hence be commercially impacted. All rice grown, sold or processed in California will be evaluated for characteristics of commercial impact, including rice brought into California for processing or sale, and IP protocols can be required for production, handling, transportation and storage of a given variety to prevent contamination of other rice. Several specialty rices currently being grown and successfully segregated in California (e.g., sweet, scented, basmati, arborio, and colored bran rices) may eventually be identified as having commercial impact. IP procedures for these varieties are already in place. However, traits that are not visible, such as herbicide tolerance, especially if the varieties are grown widely, will require extra vigilance to keep them separate from other similar varieties.

An advisory committee will recommend regulations to the Secretary of the California Department of Food and Agriculture pertaining to rice identified as having characteristics of commercial impact. The advisory committee will consider each variety separately and render a judgment, using science, economics and market experience, as to whether a given attribute has the potential for commercial impact. If it does, the committee will then establish terms and conditions of production, transportation, drying and storage to segregate the commodity from other rice types. These may include the method of seed application to prevent 3.13

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contamination of neighboring fields, buffer zones between fields, handling requirements to prevent mixtures, and other IP requirements.

An expressed intent of the Act is to encourage research and development of new types of rice. However, to prevent contamination and introduction of exotic pests, the committee must approve research protocols to ensure that the research will not have negative commercial impact. Researchers will be required to submit their research protocols, location of the research and acreage to the advisory committee and follow required procedures. Specific attributes of the rice for research do not have to be revealed. “Research” is limited to 50 or fewer acres of a single type of rice. The advisory committee also reviews procedures for rice brought into the state from other states or countries for research purposes. Current state or federal regulations for bringing such rice into California will apply unless the committee can justify that they are not acceptable. This Act does not apply to rice research conducted by the University of California except when such rice enters the channels of trade.

Separate from the work of the advisory committee, the Act allows the CRC to establish a voluntary program to certify any verifiable attribute of rice. Certified rice may be labeled with the words “This lot of rice certified (specified attribute) in accordance with the California Rice Certification Act of 2000.” Certifiable attributes include any of those characteristics that can be verified, such as origin, scent, herbicide tolerance, colored bran, mochi quality, variety, etc. One may certify, with the appropriate documentation and procedures, that a given lot of rice has or does not have a particular attribute. Hence, rice could be certified as non-transgenic or free of colored bran. Rices with and without commercial impact and seed, rough, and milled rice can all be certified. The Act does not certify rice as organic, although specific attributes of organic rice could be certified.

Variety and Harvest Considerations

Short and medium grain rice typically produce higher head rice yields (HRY) than does long grain rice. This is due to the more rounded, thicker, and harder kernels of medium grains. Additionally, earlier-maturing varieites may yield less head rice than latermaturing varieties, which is thought to be a result of grain filling processes.

Figure 1. The moisture content of individual kernels varies due to the pattern of flowering within a panicle.

Flowering patterns with the panicle vary somewhat between varieites. Anthesis (flower opening) begins at the top of the panicle and proceeds downward, a characteristic present in all California varieites and referred

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to as nonsynchronous flowering. The number of days required for flower opening ranges from 4 to 8 depending on the variety (Figure 1). The delay in anthesis from the top to the bottom also means that all flowers do not reach the stage of development that is sensitive to low temperature induced pollen sterility at the same time. Brief periods of low temperature result in sections of the panicle being “blank”. Correspondingly, the range of moisture content of individual kernels within a panicle can vary from 15 to 30 percent moisture content even though the average may be around 24 percent (Figure 2). Research has shown that the kernels at 15 percent moisture or less are likely to fissure when exposed to several hours of dew. Rice harvested at a moisture content of 18 percent may contain a large portion of individual kernels with moisture contents as low as 10 percent. There is inherent risk if standard harvesting procedures are adopted that uses an average moisture content of 18 percent as the time to harvest a given field.

Figure 2. The range of kernel moisture content in a sample may be 15 perecnt or more.

The range of maturity (i.e. harvestable moisture content) can be further accentuated by within-field variability in plant growth and development. Such variation is attributable to such things as variable water depth, the uneven application of nitrogen fertilizer, water temperature, or soil type. Research showed that the moisture content in a California rice field can range from 10 to 22 percent under routine farm management practices (Figure 3). Without prior knowledge of specific field, a simple “nosing in” of the combine to check moisture content can be misleading.

Environmental Effects on Head Rice Yield

Rice harvested at low moisture content often Figure 3. Moisture content at harvest can vary widely due to does not produce low head rice quality if it management and soil type. has not been exposed to rehydrating conditions. During the dry north wind periods that commonly occur during harvest, rice can dry to quite low moisture contents and still produce good milling quality because dry conditions prevent dew formation. 3.15

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However when the north wind ceases and dew forming conditions return, head rice yield drops. In weather conditions with high dew point

Figure 4. Diurnal fluctuation in rice grain moisture before, during, and after a north wind period.

temperatures, rice can rehydrate to fairly high moisture contents, levels that normally associated with high head rice yield (Figure 4).

Rice that rehydrates after a north wind can produce poor head rice quality even though it is harvested at the recommended moisture content. The history of rice moisture content is an important aspect of understanding the head rice yield produced in a particular field. Soil type also influences the time course of head rice loss. For example, a more rapid decline in head rice yield would be expected on light-textured soils exposed to dry, windy conditions.

Figure 5. Head rice yield as related to harvest moisture content before, during, and after a dry north wind period in 2003 and 2004, Biggs, CA.

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vest moisture content dropped 6.2 and 8.2 percentages points by the end of the windy period (Figure 5). During the north wind head rice yield declined by over 8 points in both years. Interestingly, growers’ return per acre decreased by only $0.08 and $0.17 per cwt in 2003 and 2004, respectively (Table 9). During the dry weather, reduced drying costs offset most of the head rice yield loss. Harvest date

2003

2004

Oct. 6

Oct. 13 Oct.16 Oct. 4

Oct. 11 Oct. 15

Moisture content (%) 24.3 18.1 19.6 22.8 14.6 14.3

Head Rice yield Grower Return (%) ($/cwt) 63.8

5.63

45.8

5.01

55.6 58.2 49.7 25.3

5.55 5.46 5.29 4.04

Table 9. Rice quality and value before, during, and after a dry north wind period in 2003 and 2004 for M-202, Biggs, CA.

Typically, the west side of the Sacramento Valley experiences more north wind days than areas on the east side (Figure 6). The number of windy days during harvest ranges froma low of 1.0 around Nicolaus to around 4 near Orland.

Sampling for Harvest Moisture Content

Rice moisture content may fluctuate by 5 or more percentage points during a 24 hour period before and after a north wind period. When evaluating a field in preparation for harvest, it is important to sample at a consistent time of day, such as around noon. By doing so the moisture samples are comparable between days and provide a clearer picture of the dry down rate of the rice. Rice will generally dry down at a rate of about 0.5 percent per day, northwind and high temperatures not withstandFigure 6. Average number of north wind days at selecting. For best accuracy, use a harvester to cut the ed locations in the Sacramento Valley. Data based on sample to provide the best representation of the 10-year averages. true moisture content. Alternatively, one can hand strip heads from random locations. Be sure to to take some the sample from the lower, less-mature panicles. Avoid taking just the ripe grains from the topmost panicles; this will produce a sample with a higher moisture reading than would a combine cut. 3.17

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Harvest Moisture Range by Variety

As a general rule the newer Calrose varieties (i.e. M-105, M-205, and M206) can be harvested at lower moisture contents than the older varieties (i.e. M-104, M-202, and M-401). Head rice yield is fairly stable in the newer varieties down to harvest moisture contents of around 18 to 19%. Good milling returns below this moisture content are weather dependent. Consequently harvesting low moisture rice should be an annual management decision based based on the liklihood of long periods of dew. Harveting low moisture rice should not be standard practice across years. High head and total yields observed in recent years are in part due to weather. Seven of the last ten years had relatively few dew events of eight hours or longer (Figure 7). For example in 2011 there were only two in nights were extended periods of dew and none in 2012. However in 2007 there were 7 continuous days of heavy dew during peak harvest (Table 10). This adversely affected head rice yields resulting in 15 and 30 percentage point loss in M-206 and M-202, respectively.

Figure 7. The percent head rice yield (HRY) of M-206 and M-202 across a range of moisture contents when exposed to repeated dew events..

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Table 10. Total number of hours of dew at the Rice Experiment Station during harvest season , 2003 – 2012. Sept 21 22 23 24 25 26 27 28 29 30 Oct.1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

2003 16 16 14 11 16 16 16 11 17 16 17 16 14 13 16 16 15 16 14 1 12 15 3 15 16 16

2004 14 14 14 14 15 11 14 12 11 14 14 14 14 12 10 14 8 10

5 8

2005 2 4

5

3 6 2

2 8

8 8

2006 2 2 5 3 5 6 7 13 11

2 1 4 8 10 5 1

2007 11 12 8 5 2 13 8 6 1 2 4 6 4 2 4 10 13 16 16 12 12 17 16 5 5 13 7 7

2008 2

2009

2

2011

2012

11

9 18 10 12 11 4

2 3 2 6 4 1

4 3 1

2 3 14 7 12 10 9 9 8 11

Reducing Variability in Quality Appraisal Samples

Variability and error in appraisal samples can be minimized by

collecting a representative sample; do not use a single catch can sample,

drying samples with room temperature air to maximize head rice quality,

drying samples to the same moisture contents, because low-moisture samples have slightly, higher head rice quality than samples at 14 percent moisture content, 3.19

2010

8 9 8 1 3 4

16 4

1 6 4

3 6 4

3 5

4 2 3

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using a standard multi-sample vacuum probe and a splitter to obtain the needed amount.

Analysis of replicated head rice samples appraisals by the CDFA showed that results fall within a range of 4.8 percent (± 2.4 percentage points). Variability was greater when the samples were appraised within a few days of drying, but did not change after longer periods of storage (Figure 8).

Sample Drying

Air temperature used for sample drying can affect head rice quality. Maximum quality is achieved by using air at a constant room temperature of 75° F or lower (Figure 8). If the air is heated, the rice should be exposed to warm air only periodically and allowed to temper between exposures. For example, the California Warehouse Association recommends heated air at 100° F followed by a 4-hour tempering before the next 30 minute exposure. This procedure produces head rice yields about 2.5 percentage points lower than the room temperature air method.

Figure 8. Variability and error in head rice yield results associated with appraisal sample collection, sample drying method, and sample analysis.

Sample Moisture

Sample moisture content at milling appraisal affects head rice yield. For example, medium grain rice gains about 2 percentage points of head rice when the sample moisture drops from 13.5 to 12 percent. Short grain rice is less affected by sample moisture. In contrast, long grain rice may have a 6-point spread over this range of grain moisture content.

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Appendix A - History of California Rice Varieties The short grain varieties, predominantly Caloro and Colusa, occupied essentially all of California's production until the late 1950's. The state's production shifted to Calrose following its release in 1948. California's short grain acreage continued to decline due to the success of Calrose and its progeny that currently occupy more than 80 percent of the rice acreage. Long grain, waxy short grains, aromatic long grains have been developed but have never occupied a large percentage of California's rice production. A detailed review of California's rice history from it's beginnings to 1980 had been prepared by J. H. Willson (Willson 1979).

The accelerated rice breeding program initiated in 1969 began delivering new rice varieties to growers beginning in 1976. The successful development of semidwarf Calrose mediums grains was accomplished by Rugter et al. (1977) through induced breeding and Carnahan et al. (1978) through backcrossing. These founding semidwarfs formed the germplasm pools that have allowed the development and release of 19 improved medium and short grain California varieties. The medium grain decedents of Calrose were selected to have Calrose cooking and processing characteristics and are predominantly commercially commingled in drying, storage, and utilization.

The California breeding program began to develop adapted long grains from different parentage for California. Tseng et al. (1984) released the well adapted and productive L-202. L-202 has been a successful parent in the development of recent long grain varieties Cypress and Cocodrie developed in Louisiana. L-202 seed was also exported to Spain and renamed “Thaibonnet” and it has become the major long grain variety grown in that region. Additional long grains were released by Tseng et al with improvements in agronomic, milling, and cooking quality; however, long grain production still occupies